This invention relates to portable gas appliances such as flashlights or gas torches.
In such appliances, the fuel is typically a liquid fuel that is supplied to the appliance from a pressurized fuel supply reservoir. A controller desirable controls the flow of fuel from the fuel supply and shuts off the fuel supply when desired. It is also necessary to substantially reduce the pressure of liquified fuel as it passes out of the supply to the appliance to aid in metering of vaporized liquified fuel. In many such appliances, the operating characteristics of the appliance may change widely depending on the operating temperature and the orientation of the fuel supply. If liquid fuel is passed to the appliance without complete vaporization, a markedly increased burn rate may result. A check valve arrangement, for example of the type shown in co-pending U.S. patent application Ser. No. 08/338,000, filed Nov. 10, 1994 now U.S. Pat. No. 5,522,722 and entitled FUEL CONTROL, the disclosure of which is expressly incorporated herein, is of use in reducing these problems. However, operating characteristics of the check valve may drift, due to factors such as impurities in the fuel, and periodic replacement of the check valve may be advisable.
In accordance with one aspect of the invention, there is provided a gas powered appliance that includes housing structure with a fuel inlet port and recess structure for receiving fuel canister structure in communication with the inlet port. Fuel supply conduit structure in the housing structure has an outlet port, and fuel control structure in the housing structure controls flow of fuel from the inlet port through the fuel supply conduit structure to the outlet port. The fuel canister structure is adapted for releasable disposition in the recess structure, and has a body portion, outlet valve structure on the body portion for coupling to the inlet port when the fuel canister structure is disposed in the recess structure, and check valve structure releasably disposed in the recess structure in communication with the outlet valve structure for preventing liquid fuel from reaching the flow control structure when the fuel canister structure is disposed in the recess structure.
In particular embodiments, the check valve structure is in the fuel canister structure, and in other embodiments, the check valve structure is releasably attached to the fuel canister structure. In preferred embodiments, the appliance is a portable light source and has a handle portion sized to be grasped in a hand, and a head portion of larger dimension than the handle portion that includes lens structure. Mantle structure is composed of multifilament metal oxide strands, supported on fuel supply conduit structure adjacent the outlet port and ignitor mechanism is disposed in the housing structure for igniting fuel to cause the mantle structure to become incandescent and emit optical radiation. The fuel canister structure contains a liquid hydrocarbon fuel such as isobutane, propane, gasoline, or the like.
The check valve structure may be of various types such as a flat gasket type, a duck bill type, or a diaphragm type.
Preferably, the check valve structure includes a check valve diaphragm member disposed in the check valve chamber that divides that check valve chamber into upstream and downstream chambers. Check valve structure is carried by the check valve diaphragm and valve seat structure is disposed in the upstream check valve chamber, the check valve structure being adapted to close when the pressure differential between the upstream and downstream check valve chambers is less than a predetermined value such that fuel does not flow from the upstream check valve chamber to the downstream check valve chamber. In particular embodiments the check valve pressure differential that causes the check valve structure to close is in the range of 5-12 pounds per square inch.
In accordance with another aspect, there is provided a fuel canister for use with a portable gas appliance, the gas powered appliance including housing structure with a fuel inlet port and recess structure for receiving fuel canister structure, fuel supply conduit structure in the housing structure that has an outlet port, and fuel control structure in the housing structure for controlling flow of fuel from the inlet port through the fuel supply conduit structure to the outlet port. The fuel canister structure is adapted for releasable disposition in the recess structure and includes outlet passage structure for coupling to inlet port structure of the gas appliance, outlet valve structure disposed in the outlet passage that has a normally closed position preventing flow of fuel from the fuel canister and an open position, and check valve structure in the body of the fuel canister and coupled to the outlet valve structure. The check valve structure is adapted to open when the pressure differential between the upstream check valve chamber and the downstream check valve chamber is greater than an predetermined value so that fuel flows from the upstream check valve chamber to said downstream check valve chamber.
In accordance with another aspect of the invention, there is provided a releasable check valve assembly for releasable coupling to a fuel canister. The check valve assembly has outlet passage structure for coupling to inlet port structure of a gas appliance, inlet passage structure for coupling to the outlet port of the fuel canister, control valve structure disposed in the outlet passage that has a normally closed position preventing flow of fuel to the gas appliance and an open position, check valve structure in the detachable assembly, the check valve structure being disposed between the inlet passage and the control valve structure for preventing liquid fuel from reaching the control valve structure when the fuel canister is coupled to the gas appliance, and releasable coupling structure. The releasable coupling may be of the resilient snap type, the screw type or a bayonet type for example. In a particular embodiment, the check valve structure includes a check valve diaphragm member that defines the check valve chamber into upstream and downstream chambers, and the control valve structure includes a valve member that is biased against a resilient gasket member to close the outlet port.